Megafauna community structure and trophic relationships at the recently discovered Concepción Methane Seep Area, Chile, ∼36°S

Abstract Sellanes, J., Quiroga, E., and Neira, C. 2008. Megafauna community structure and trophic relationships at the recently discovered Concepción Methane Seep Area, Chile, ∼36°S. – ICES Journal of Marine Science, 65: 1102–1111. The fauna, community composition, and trophic support of the newly discovered Concepción Methane Seep Area (CMSA) are compared with those at a nearby non-seep control. The assemblage of chemosymbiotic bivalves is defined by eight species, including the families Lucinidae, Thyasiridae, Solemyidae, and Vesicomyidae. Seep polychaetes are represented by Lamellibrachia sp. and two commensal species of the vesicomyid Calyptogena gallardoi. Although taxonomic analysis is still under way, most of the chemosymbiotic species seem to be endemics. The CMSA is a hotspot for non-seep benthic megafauna too; 101 taxa were present, but most of them are colonists or vagrants (i.e. not endemics of methane seeps). Isotope analysis supported the belief that non-symbiont-bearing species utilize photosynthetically fixed carbon, because they were isotopically distinct from the chemosymbiotic bivalve species present. It is our opinion that, at this site, which underlies one of the most productive coastal upwelling regions of the world, spatial heterogeneity and the availability of hard substratum, generated by the presence of authigenic carbonate crusts, are more important factors in attracting non-seep fauna than the availability of locally produced chemosynthetic food.

Download Full-text

Trophic Relationships between Macroinvertebrate and Fish Communities in St. Petersburg Methane Seep in the Abyssal Zone of Lake Baikal

Сибирский экологический журнал ◽

10.15372/sej20170207 ◽

2017 ◽

Keyword(s):

Lake Baikal ◽

Fish Communities ◽

Trophic Relationships ◽

Methane Seep ◽

Abyssal Zone

Download Full-text

Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315406014494 ◽

2006 ◽

Vol 86 (6) ◽

pp. 1443-1447 ◽

Cited By ~ 3

Author(s):

D. Fourgon ◽

G. Lepoint ◽

I. Eeckhaut

Keyword(s):

Stable Isotopes ◽

Potential Benefit ◽

Feeding Habits ◽

Isotope Analysis ◽

Tracer Experiment ◽

Trophic Relationships ◽

Nitrogen Stable Isotopes ◽

Carbon And Nitrogen ◽

C And N ◽

The One

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiuroids, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiuroids. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate δ13C values between both adult species. The high proportion of 13C in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston from their associated host, O. scolopendrina.

Download Full-text

Masters of Wine on Twitter: presence, activity, impact and community structure

Wine Economics and Policy ◽

10.36253/wep-9055 ◽

2021 ◽

Vol 10 (1) ◽

pp. 73-88

Author(s):

Enrique Orduña-Malea ◽

Cristina I. Font-Julian ◽

José Antonio Ontalba-Ruipérez ◽

Raúl Compés-López

Keyword(s):

Social Media ◽

International Trade ◽

Community Structure ◽

Descriptive Statistics ◽

Wine Industry ◽

The Internet ◽

The World ◽

Credible Information ◽

Do So ◽

The Way

Globalisation, the Internet and social media have changed the kind of actors with influence in the wine industry and the way these actors create signals to communicate credible information about experience and trust attributes. Among the most prestigious experts in the world of wine are the Masters of Wine (MW). Although initially devoted to international trade, they have spread their activities and their opinion is more and more appreciated by producers and consumers. The main objective of this article is to determine this community of experts’ behaviour on Twitter. In order to do so, four factors (presence, activity, impact and community) have been considered. All Twitter profiles belonging to users awarded with the MW qualification were identified and analysed. In addition, a set of 35,653 tweets published by the MWs were retrieved and analysed through descriptive statistics. The results show MWs on Twitter as high attractors (number of followers), moderate publishers (original contents published), moderate influencers (number of likes and retweets), and low interactors (number of friends and mentions to other users). These findings reveal that the MW community is not using Twitter to gain or reinforce their reputation as an accredited expert in the wine industry, giving more influential space on Twitter to consumers and amateurs.

Download Full-text

Community structure and trophic relationships of the fish fauna of an estuarine Posidonia Australis seagrass habitat in port hacking, new South Wales

Aquatic Botany ◽

10.1016/0304-3770(84)90081-0 ◽

1984 ◽

Vol 18 (1-2) ◽

pp. 71-87 ◽

Cited By ~ 49

Author(s):

J.J. Burchmore ◽

D.A. Pollard ◽

J.D. Bell

Keyword(s):

Community Structure ◽

New South ◽

New South Wales ◽

Fish Fauna ◽

Trophic Relationships ◽

Seagrass Habitat ◽

South Wales

Download Full-text

Marked contrast in wind-driven upwelling on the southeastern Nova Scotia coast in July of two years differing in ENSO conditions

Oceanological and Hydrobiological Studies ◽

10.1515/ohs-2020-0008 ◽

2020 ◽

Vol 49 (1) ◽

pp. 81-87 ◽

Cited By ~ 4

Author(s):

Ricardo A. Scrosati ◽

Julius A. Ellrich

Keyword(s):

Nova Scotia ◽

El Niño ◽

Coastal Upwelling ◽

El Nino ◽

Atlantic Coast ◽

Future Research ◽

Recent Book ◽

Limited Information ◽

Marked Contrast ◽

The World

AbstractUpwelling occurs on several coasts of the world, but it has mostly been studied on eastern ocean boundaries. We investigated upwelling on a western ocean boundary for which limited information exists. Using daily in-situ data on sea surface temperature (SST), we found a marked contrast in coastal cooling between July 2014 (pronounced) and July 2015 (weak) at two locations 110 km apart on the Atlantic coast of Nova Scotia, Canada. These findings are consistent with a marked interannual difference in wind-driven upwelling. On the one hand, southwesterlies (which cause upwelling on this coast) were more frequent in July 2014 than in July 2015. On the other hand, Bakun’s upwelling index (which is based on wind data and geographic information) indicated that coastal upwelling was more common and intense in July 2014 than in July 2015, while the reverse was true for downwelling. Interestingly, a strong El Niño event occurred in July 2015, while no El Niño (or La Niña) conditions happened in July 2014. In a recent book evaluating upwelling systems around the world, the system that is the focus of the present study was not included. Therefore, our findings should stimulate future research on upwelling on the Atlantic Canadian coast, in that way helping to further develop the knowledge base for western ocean boundaries.

Download Full-text

Community structure in the World Trade Network based on communicability distances

Journal of Economic Interaction and Coordination ◽

10.1007/s11403-020-00309-y ◽

2020 ◽

Author(s):

Paolo Bartesaghi ◽

Gian Paolo Clemente ◽

Rosanna Grassi

Keyword(s):

Community Structure ◽

Numerical Analysis ◽

World Trade ◽

Metric Spaces ◽

Trade Network ◽

Distance Threshold ◽

Alternative Clustering ◽

Mesoscale Structure ◽

Long Range Interactions ◽

The World

AbstractIn this paper, we investigate the mesoscale structure of the World Trade Network. In this framework, a specific role is assumed by short- and long-range interactions, and hence by any suitably defined network-based distance between countries. Therefore, we identify clusters through a new procedure that exploits Estrada communicability distance and the vibrational communicability distance, which turn out to be particularly suitable for catching the inner structure of the economic network. The proposed methodology aims at finding the distance threshold that maximizes a specific quality function defined for general metric spaces. Main advantages regard the computational efficiency of the procedure as well as the possibility to inspect intercluster and intracluster properties of the resulting communities. The numerical analysis highlights peculiar relationships between countries and provides a rich set of information that can hardly be achieved within alternative clustering approaches.

Download Full-text

Trophic relationships of breeding Red-necked Grebes (Podiceps grisegena) on wetlands with and without fish in the Aspen Parkland

Canadian Journal of Zoology ◽

10.1139/z09-132 ◽

2010 ◽

Vol 88 (2) ◽

pp. 186-194 ◽

Cited By ~ 7

Author(s):

C. E. McParland ◽

C. A. Paszkowski ◽

J. L. Newbrey

Keyword(s):

Egg Production ◽

Trophic Position ◽

Isotope Analysis ◽

Trophic Levels ◽

Trophic Relationships ◽

Breeding Sites ◽

Top Predators ◽

Aspen Parkland ◽

Wintering Areas ◽

Podiceps Grisegena

Dietary overlap between waterbirds and fish in many freshwater systems can lead to competition for food resources and changes in the trophic position of top predators. We used stable isotope analysis of carbon and nitrogen from egg tissues to document differences in the trophic position of breeding Red-necked Grebes ( Podiceps grisegena (Boddaert, 1783)) on wetlands with and without fish in the Aspen Parkland of Alberta, Canada. Grebes occupied higher trophic levels in the presence of fish than in their absence, suggesting that small-bodied fish in Aspen Parkland food webs may lengthen food chains in which grebes are top predators. A mixed diet of invertebrates and fishes may be adaptive for grebes in this highly variable ecosystem where fish colonize wetlands in wet years and are extirpated in dry years. Carbon analyses indicated that female grebes likely obtained resources for egg production from breeding sites and not from wintering areas, as eggs had similar δ13C values to wetland primary producers, invertebrates, and fishes.

Download Full-text